Stone-cutting chisel.



H. DEHL.

STONE CUTTING CHISEL. APYLIUATION FILED NOV. 1, 1910.

Patented May 27, 1913.

HEINRICH DEI-IL, OF COLOGNE-LINDENTHAL, GERMANY, ASSIGNOR TO BEBGISQHMARKISCHE STEININDUSTRIE, AKTIENGESELLSCI'IAFT,

RHINE, GERMANY.

or COLOGNE-ON-THE- STONE-CUTTING CHISEL.

Specification of Letters Patent.

Patented May2'7, 1913.

Application filed November 1, 1910. Serial No. 590,181.

To all who-m it may concern Be it known that I, HEINRICH DEHL, engineer,residing at 120 Gleuelerstrasse, Gologne-Lindenthal, Kingdom of Prussia,Germany, have invented certain new and useful Improvements inStone-Outting Chisels, of which the following is a specification.

For cutting wedge holes in rocks and the like chisel-like tools areemployed, which, having a wedge shape, are provided with cutting bursarranged either transversely or longitudinally and bordered on bothsides with grooves, or with a beveled serrated edge. WVhereas thechisels provided with transverse burs offer a considerable resistance tothe feed in consequence of the large working and frictional surfacessimultaneously attacking on all sides, and will, particularly at thecommencement of the cutting operation cause the portions of the rockaround the hole to be crumbled off, or even lead to the lower, weakerprojecting burs of the tool being damaged or broken off, thedisadvantage of the longitudinally burred wedge chisels consists in thefact that a considerable superficial friction between the rock and thesides of the tool between the cutting edges is produced after the toolhas been driven a good piece into the rock. These disadvantages of bothtypes of tools may be avoided by providing, according to the presentinvention both the sides and the face ends of the chisel with aplurality of pyramid shaped projections or cutting points so that thesurface of the chisel assumes a checkered or granulated appearance.

In the accompanying drawing two types of chisels according to thepresent invention are exemplified.

Figures 1 and 2 are a side and end view respectively of a piece of achisel with the cutting projections arranged in parallel rows crossingeach other at right angles. Fig. 3 is a side view of a piece of a chiselwith the cutting projections arranged in parallel rows but alternatelyto each other.

The chisel A shown at Figs. 1 and 2 has for its working part the shapeof a wedge and is provided on its two parallel sides as well as on itstwo inclined opposite sides with two series of parallel grooves a and b,

which are inclined to its longitudinal central axis in oppositedirections, the grooves a a crossing the other ones I) b at rightangles. As all the grooves a b are of a V- cross section and leave sharpedges 0 c and (Z d between them, it follows, that on the part of thechisel covered with crossing grooves numerous pyramidal projectionse cwith sharp points are formed. The sharp points of these pyramidalprojections e e are surrounded on all sides by gaps and will eachindividually attack only a small portion of the rock, each point cuttingindependently, and will therefore meet with a small resistance only, sothat at the commencement, during the course and up to the end of thecutting operation no considerable increase of the difliculties will beobserved,

and the work will be performed in a smooth and rapid manner. The spacesbetween the several points facilitate the removal of the rock dustproduced in cutting.

lVhere so preferred, the pyramidal projections f f on the wedge-chiselmay be arranged in parallel rows and made to alter-,

nate with the projections in the neighboring rows, as is clearly shownat Fig. 3.

The wedge-chisel may be made of any suitable shape and size and may bearranged to be fitted with its shank 9 into any power-driven cuttingapparatus, provided with a suitable chuck.

I claim:

1. A wedge shaped chisel for cutting tapered holes in rocks, provided onall sides with a plurality of sharply pointed pyramidal projections.

2. A wedge shaped chisel for cutting tapered holes in rocks, provided onall sides with a plurality of sharply pointed pyramidal projections;said projections alternating in the longitudinal direction of the tool.

3. A wedge shaped chisel for cutting tapered holes in rocks, said chiselhaving a plurality of pyramid shaped projections terminating in cuttingpoints and arranged in staggered relation throughout the cutting area ofthe tool; said projections arranged in parallel rows in two directionsforming diagonal grooves between them, said grooves constitutingchannels for the removal of the material chipped by the cutting edges.

4. A wedge shaped chisel for cutting taceding neighbor, whereby eachprojection pered holes in rocks, said chisel having a forms anindividual cutting tool. 10 plurality of pyramid shaped projections ar-In testimony whereof I hereto aflix my ranged along its Workingsurfaces; said signature in presence of two witnesses.

5 projections forming a series of cutting edges HEINRICH DEHL.

along the sides of the chisel, each following In presence o-f projectionextending farther out from the LOUIS VANDORY, longitudinal axis of thewedge than its pre- BESSIE L. DUNLAP.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents. Washington, D. C.

